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Any process that interferes with this normal development may cause tethering. Tetherine may be defined as a low position of the spinal cord caused by and/or associated with fixation (tethering). the most common cause
of this process is a collection of fat in the distal part of the spinal cord that may come out to a collection of fat under the skin (lipomeningocele). Another common cause is a thickened distal projection of the spinal
cord called the filum terminale. Part of this thickening may include fat. The cases of tethering that have been described wtih Rubinstein-Taybi syndrome are usually associated with a thickened filum terminale.
Symptoms and signs associated with tethering may include a midline lumbar skin lesion such as a fat tumor (lipoma), a birth mark, hemangioma or a dimple (pit). Ther emay be back pain scoliosis, bowel and urinary incontinence,
leg and foot deformities. Early in life many children are asymptomatic. Symptoms and signs tend to occur with growth spurts.
The most definitive diagnostic test is the MRI scan. In some institutions this may include a MRI movie (cine study) to evauate spinal cord movement. Early in infancy ultrasound of the spine is a good screening tool.
It is recommended that all patients in which there is suspicion of a tethered spinal cord should have imaging. This suspicion may be based on a condition associated with tethering (Rubinstein-Taybi syndrome), external
signs such as skin lesions int he midline lumbar area, or clinical signs and symptoms. If there is a tethering demonstrated on imaging then surgical repair is recommended even if there are no clinical signs and
symptoms. Anecdotal data mainly based on children with lipomeningocele imply that the risk of surgical repair is much less than the risk of observation. There are no prospective randomized studies to evaluate this
form of management including those with Rubinstein-Taybi syndrome.
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